1. Field of the Invention
This invention relates to a method and apparatus for automatically assembling a wire harness arrangement which can be used on a wide variety of electrical devices. More particularly, this inventions relates to such a wire harness assembly arrangement which provides for terminating and routing individual sections of wire that combine to form the wire harness assembly typically used to electrically connect the various components that make up today's complex electronic and electrical devices. Additionally, this invention relates to such a method and arrangement as can be used in conjunction with a robotic manipulation system to facilitate the performance of such wire harness assembly operation.
2. Description of the Prior Art
It is known that, along with the recent growth in the application of miniature electronic circuit components designed to improve practically all aspects of our lifestyles, there comes a need to more accurately and efficiently perform the wiring and assembly operations that comprise a large portion of the electrical devices that make use of these electronic components. Additionally, because such electrical devices typically employ a variety of integrated circuits as well as other electronic and electrical devices which vary in size and require correspondingly variable gauges and lengths of wiring to interconnect them, the automation of such an operation would be advantageous over the manual performance of such due to the space limitations under which this wiring operation must be performed.
It is further known that because of the cost improvement that has occurred in the electronic component markets, when considering the overall costs of an electrical device, the cost of assembling the device has increased significantly in proportion to the material component cost associated with the device. As such, there has been an increased desire to maximize the performance of the wire harness assembly operation while at the same time, maintaining or improving the cost level of the assembly process relative to the material costs.
A further problem that has been encountered in automatic wire harness assembly operations has been that, during the routing process, a segment of wire may get tangled upon itself or possibly damaged such that the routing step cannot be properly completed. It is therefore desireable to provide an arrangement that, during the wire preparation step, the wire segment is arranged in a manner to prevent tangling during the subsequent routing step.
In meeting these objectives, there have been several arrangements introduced which are either directed to specific problems related to previously used automatic or manual wiring techniques to which are directed to distinct needs of a particular industry. One of the earliest automatic cable harness assembly arrangements can be found in U.S. Pat. No. 3,885,161 issued to Tarbox et al. on May 20, 1975 and which is assigned to the Hughes Aircraft Company. In this patent, the cable harness assembly arrangement provides that the routing of the wire sections is done along predetermined paths which are associated with cable groupings. This approach does not provide for the essentially simultaneous terminating and routing operations that maximize efficiencies with a wire harness arrangement as found in the more recent developments in this area. Nor does this arrangement easily lend itself to a more random wire distribution as can occur when the wire harness assembly is not restricted to a cable type of layout.
Another example of a wire harness assembly arrangement which is directed to a specific need of a particular industry can be found in U.S. Pat. No. 4,126,935 issued to Rhines et al on Nov. 28, 1978 and assigned to AT&T, Bell Laboratories. The approach taught in this patent deals with the mass termination of groupings of twisted pairs of wires onto slotted beam connector blocks. As this approach is intended for use in the communications industry, special features are provided such as a pair indexing head, a comb and a presser head for selectively terminating individual pairs from a bundle of pairs.
Yet another wire harness assembly arrangement can be found in the British Patent No. 2,025,272 issued to R.D. Gibbons on Jan. 23, 1980. In this patent, wire is acquired from a feeding device, prepared for termination and routed among a pattern of pins set into a formboard. This arrangement was found satisfactory for use with light gauge wiring and where the accuracy of the end portion of the wire was not a critical factor. However, where it was necessary to provide for a variety of sizes of wire and to have control over the handling and termination of the end portion of the segment of wire, this arrangement could not effectively be used.
Other wire harness assembly arrangements can be found in U.S. Pat. Nos. 4,593,452 issued to Keahey et al on June 10, 1986 and assigned to Amp Inc., and 4,677,734 issued to Bloch et al and assigned to the Boeing Company. In U.S. Pat. No. 4,593,452, a robotic system having a gripper assembly, manipulates various jigs and connectors to perform the wire lacing operation. Additionally, the wire is supplied from a holder having wire feed wheels and a severing mechanism. In U.S. Pat. No. 4,677,734, a robotic system includes a wire preparation subsystem, a wire reeling subsystem, and a wire queuing subsystem among other subsystems.
U.S. Pat. No. 4,653,159 issued to Henderson et al. on Mar. 31, 1987 and assigned to the same assignee as the present application, discloses a wire harness assembly arrangement using a conventional robotic transport system to perform the wire preparation and harness formation operations.
Though the heretofore discussed wire harness assembly arrangements provide distinct advantages and benefits to the particular problems to which they are directed, there remains a need to provide a single wire harness assembly arrangement which can accommodate a wide variety of industrial situations, can operate using any type or size of available wiring material, does not require fitting the robotic manipulator with different tooling ends to meet different wiring situations, and provides for the positive control of the section of wire over the entire path in which it is to be laid. Additionally, it would be advantageous if such a wire harness assembly arrangement could perform the wire acquisition phase of operation so that the wire section was uniformly distributed and stored within the tooling device thereby insuring that during the subsequent dispensing or routing phase of operation, the wire section would not become tangled or damaged in any way.